Vandals force fluids into the bill entryway of bill validators in an attempt to generate false vending signals in vending machines to obtain free product and coins. Because of a method used by vandals to perpetrate the fraud, those familiar with the vending machine industry call this fraud practice "salting". Certain vending machine types, such as can and bottle machines, are particularly susceptible to such vandalism because they are frequently placed in exposed and unprotected locations. Thefts of up to 100 cans of soda and loss of coins from the coin tubes have been reported in some locations. Further, the cost for cleaning up bill validators, coin mechanisms, and other related vending machine components after such an attack can easily exceed three hundred dollars.
The liquids injected into a vending machine opening can cause extensive damage to the component associated with that opening. In addition, the liquids may drip into other machine components and cause direct or indirect damage, increasing the cost of repair.
Attempts have been made to design an apparatus to reduce the damage from such salting attacks. For example, a rainwater/anti-salting shield for installation in vending machines was made to reduce the ingress of liquids along the coin path. Such shields are frequently swamped by the volume of the injected fluids during a salting attack, and provide no protection for a bill validator.
One company, EIC of Jenison, Mich., manufactures a "Protection Unit" for bill validators which mounts inside the bill validator on the line side of a power transformer, and includes a moisture sensor that mounts in the entrance of the bill validator. The moisture sensor circuitry operates to remove power to the validator and to provide an alarm function when liquids are sensed. However, the bill validator must be disassembled for installation of the unit, and when moisture is sensed the vend line is not disconnected. Further, the unit does little to reduce the collateral damage produced by a salting attack. In addition, the moisture sensor of this unit is potentially exposed to tampering. Yet further, cleanup requires access to the moisture sensor.
The Mid-South Services Company of Dallas, Tex. produces the "Vender Defender", which is a shield-type device for limiting the amount of fluid injected, into the entrance of a bill validator. This unit does nothing to remove power or provide other protection in the case of a salting attack.
Other means, such as using slow blow fuses and ground fault interrupters, have been implemented to protect vending machines and their components from salting attacks. While these methods provide some protection, they tend to act only after damage has been done to a vending machine component such as the bill validator.